A member of the palygorskite-sepiolite group with a composition of approximately (Mg8-y-zR3+yvz) (Si12-xR3+x) O30 (OH)4 (OH2)4 . R2+(x-y+2z)2 (H2O)8, where R are cations, v are vacancies, and x, y, and z are compositional parameters.
See palygorskite-sepiolite group